Products and services are often discussed in public reviews, online and in other media. Reviews are typically written by professional critics, by experts, and/or by ordinary consumers. Reviews often discuss particular features of a reviewed item, and provide the reviewer's subjective opinions regarding the item (product or service) and its features. A rating may be given as part of a review, to indicate an item's relative merit, e.g., by giving the reviewed item three stars within a range from zero stars (worst) to five stars (best). Reviews may be unpaid, or the reviewer may be compensated for providing the review.
In electronic commerce, product reviews are often provided on shopping sites to give consumers a chance to rate and comment on products they have purchased. Such reviews are often published near or on the web page(s) that offer the reviewed product. Other consumers can read these reviews when considering items for purchase. When several reviews have been given, an overall rating based on the individual ratings can be automatically calculated and displayed on the product page. Reviews may be anonymous, semi-anonymous (associated only with a screen name or user name), or attributed to a person whose offline name is given.